Fingerprint Sensor Electrode Grouping for High-Resolution Sensing
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Solution Overview
Problem
Current fingerprint sensing devices face challenges in achieving high resolution and sensitivity, leading to inaccurate detection of fingerprint patterns due to the small distances between electrodes, which results in decreased sensitivity and accuracy.
Innovation Solution
The fingerprint sensor employs a configuration where driving electrodes are grouped into multiple driving groups, and sensing electrodes are grouped into sensing groups, allowing for the application of driving signals to multiple electrodes simultaneously, increasing the size of the activated area and enhancing signal strength, along with a processor that calculates mutual capacitance by adjusting weights based on node locations and channel overlaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the distance between electrodes is reduced to increase resolution, then the resolution is improved, but the sensitivity decreases
Solution Approach 1:
Multiple driving electrodes are grouped into a single driving group, and multiple sensing electrodes are grouped into a sensing group. The driving signals are applied simultaneously to multiple electrodes in the driving group, and their responses are collectively measured by the sensing group. This merging approach increases the total signal strength while maintaining the fine electrode spacing needed for high resolution fingerprint detection.
Solution Approach 2:
The patent dynamically adjusts the weight coefficients of different electrode responses based on their signal strengths and noise levels. The processor selectively emphasizes stronger signals and suppresses weaker or noisier ones, optimizing the overall detection sensitivity while preserving the high-resolution capability provided by closely-spaced electrodes.
2Reliability
If driving signals are applied to multiple electrodes simultaneously to increase signal strength, then the sensitivity is improved, but the device complexity increases
Solution Approach 1:
The electrode array is segmented into discrete driving groups and sensing groups. Each group is controlled as a unit, which simplifies the control logic compared to individually controlling each electrode. The segmentation allows simultaneous activation of multiple electrodes through a unified control mechanism, increasing signal strength while managing complexity through modular group control.
Solution Approach 2:
The patent employs periodic scanning of different driving groups and sensing groups in a structured sequence. This periodic action allows the system to systematically activate multiple electrode groups over time, accumulating signal strength through temporal integration while maintaining manageable control complexity through repetitive, predictable patterns.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the sensitivity and accuracy of fingerprint detection by enhancing the strength of electrical signals and accurately calculating mutual capacitance, thereby improving the resolution and reliability of fingerprint recognition.
Implementation Method 1
a processor PU calculating the mutual capacitance from the electrical signal measured by the signal measuring unit RU
Data Source
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AI summary
Sensing sensitivity of a fingerprint sensor may be enhanced by grouping driving electrodes and driving groups. A processor of the fingerprint sensor may calculate mutual capacitance at each node on a touchpad from gross mutual capacitances in areas including a plurality of channels.